Children today are at risk of exposure to multiple environmental hazards - toxic chemicals, social stressors and the hazards of the built environment. A growing body of research indicates that environmental exposures contribute to common pediatric diseases: asthma, neurodevelopmental disorders, birth defects, obesity and type 2 diabetes and possibly also to disease in adult life. Yet few pediatricians are trained to study, diagnose, treat or prevent diseases of environmental origin, and few academic health centers have research leaders or programs in environmental pediatrics. The IOM states that there is national need to expand the scientific workforce in environmental medicine. To train the next generation of physician-scientists and academic leaders in environmental pediatrics, the Mount Sinai School of Medicine seeks renewal of its 3-year, interdisciplinary, post-residency/post-doctoral research training program in environmental pediatrics that began in 2007. Epidemiological research in environmental pediatrics is the core training theme. Two new fellows are admitted each year. Selection is competitive, and fellows are a mix of clinically trained pediatricians and doctorally trained research scientists. Emphasis is placed on recruitment of underrepresented minorities. We provide fellows with a robust methodological base and equip them with a versatile set of tools they can apply to study a wide range of scientific questions. The focus in year 1 is on education in epidemiology, biostatistics, toxicology, environmental medicine and research design to fulfill requirements for an MPH degree. In years 2 and 3, emphasis is on mentored research that generates an MPH thesis, produces manuscripts and posters, and fosters transition toward independence. Each fellow is guided by a mentor and advisors from multiple clinical and basic science departments. Courses are provided in grant-writing and responsible conduct of research. For physicians, supervised clinical experience in environmental pediatrics extends throughout the fellowship. Formal evaluation of each fellow is conducted semi-annually. An Executive Faculty Committee and an External Advisory Board have been formed. Expected outcomes include: authorship of 1-2 publishable manuscripts based on original research; authorship of 2-3 posters; completion of an MPH focused on environmental pediatrics; development in year 3 of a K08 or R01 grant proposal; and evidence of transition toward independent investigator status. This program builds on a fellowship in environmental pediatrics supported at Mount Sinai in 2002-2007 by the Academic Pediatric Association. It links to a Breast Cancer and Environment Research Center, a Pediatric Environmental Health Specialty Unit, and the Queens Vanguard Center of the National Children's Study (NCS). The program has successfully recruited 10 fellows and graduated 4. All 4 graduates are pursuing academic careers in environmental pediatrics. Fellows and graduates have published over 30 papers. One graduate is a Lead Investigator in the NCS. Another has secured an NIH K99 award.